Răspuns:
(5+3)×4=32
8a=32=>a=32:8=>a=4
(9-1)×6=48
(9-a)·6=48=>9-a=48:6=>a=9-8=>a=1
42=7×(2+4)
42=7(2+a)=>42:7=2+a=>6-2=a=>a=4
(7+2)×8=72
(7+a)·8=72=>7+a=72:8=>a=9-7=>a=2
(9-5)×9=36
(a-5)·9=36=>a-5=36:9=>a=4+5=>a=9
40=5×(9-1)
40=5(9-a)=>40:5=9-a=>a=9-8=>a=1